Method of and apparatus for making sheet metal



Dec. 1, 1936. K. c. GARDNER 2,062,875

METHOD'OF AND APPARATUS FOR MAKING SHEET METAL Filed May 13, 1935 2 Sheets-Sheet l INVENTOR.

ATTORNEYS.

w w w? a a fi I g QM Q ww v Q WM QW *W 6 mv m E S Dec. 1, 1936. c GARDNER 2,062,875

METHOD OF AND APPARATUS FOR MAKING SHEET META-L Filed May 15, 1955 2 Sheets-Sheet 2 INVENTOR aways 7 M v Z 6 ,9

% q,ew1v M1/ ATTORN E Y5 Patented Dec. 1; 1936 UNITED STATES PATENT OFFICE METHOD OF AND APPARATUS FOR MAKING SHEET METAL Application May 13, 1935, Serial No. 21,089

15 Claims.

This invention relates to strip and sheet metal and to means and methods of manufacture, and more particularly is concerned with the production of relatively wide, thin metal of very uniform thickness, and to improved apparatus and processes of making strip or'sheet metal of the desired characteristics.

In the production of strip or sheet metal of any size and thickness. and particularly strip metal of relatively thin gauge and considerable width it is desirable to obtain uniform thickness in the metal and to avoid thin edges and buckled or wavy spots therein.

Prior to my invention strip and sheet metal has been'made by rolling slabs or plates on a rolling mill which reduced the slabs or plates to rough sheet form. These roughing mills have been of the reversing mill type or the continuous or tandem' mill type. The rough sheet was then passed to other mills which rolled it down to the finished size and the desired surface. These finishing mills likewise have been of the reversing type, the continuous type or the tandem type. Ordinarily the practice has been to hot roll the sheets to rough form on the roughing mill and to cold roll the sheets on the finishing mill.

In the production of metal strip one objectionable condition which is encountered is roll defiection under rolling pressures. This deflection causes the strip or sheet metal to be formed more or less with convexly curved outer surfaces across its width. Strip metal up to certain widths can be produced within commercial tolerances on thickness variations. However, the demand for 0 and use of wider strip has increased to such an extent that as attempts are made to satisfy the demand, roll deflection and variation in sheet thickness become a very serious problem which must be overcome in order to produce strip and sheet metal which does not exceed the allowed tolerances between the thickness at the center and the edge portions of the sheet. In the prior practice of forming wide sheeton a hot roughing mill and then finishing the sheet by a coldrolling operation on a finishing mill, the error due to roll deflection has been considerably multiplied because of the many wide passes.

Another factor which results in variations in thickness during manufacture of relatively thin, wide strip metal is temperature differences in the rolls and in the metal which cause uneven contraction and expansion thereof with resulting differences in the gauge of the metal.

It is the object of my invention to avoid and overcome the foregoing and other difficulties attending the manufacture of wide sheet andstrip metal by the provision of commercially applicable means and methods for producing sheet and strip metal of any width and particularly relatively wide widths wherein the gauge or thickness of the metal is very uniform across its entire width and which is free of buckles and wavy portions.

My invention is predicated on the discovery that its stated object can be attained by longitudinally uniting a plurality of relatively narrow strips of rough formed strip metal into a single strip with a subsequent substantial reduction in thickness by a cold-rolling operation to form the sheet to the desired dimensions.

More particularly in the practice of my invention slabs or plates are hot rolled on relatively narrow mills to rough strip form with the strips ordinarily being coiled thereafter for convenience in handling. A plurality of the coils of strips is then mounted adjacent each other with the strips from the several coils being passed to mechanism for uniting the strip edges together. This operation is performed in one embodiment of my invention, by passing the several strips, with the planes of the strips at an angle to each other, to aligning and edge-working means which serve to prepare the edges for a butt-welding operation. From the edge-working mechanism the strips pass to bending means which curve the strips so that in cross section the strips form portions of a circle of relatively large diameter. While still held in the arcuate position the worked edges of the bent strips are continuously brought together and welded. The bead formed during welding is then removed, the composite strip is flattened and it is then cold rolled on a mill of the requisite width to form sheet metal of the desired dimensions.

This operation and the mechanism for eflecting it produce strip and sheet metal of the desired dimensions and particularly sheet metal of relatively thin gauge and considerable width wherein the thickness of the metal is very uniform over its entire width. The sheet metal is much more uniform than that manufactured by former processes and apparatus.

Apparatus which may be used in the practice of the invention is illustrated in the accompanying drawings wherein Fig. 1 is a plan view illustrating the arrangement of the apparatus; Fig. 2 is an enlarged plan view of the welding unit shown in Fig. 1; Fig. 3 is a side elevation of the apparatus illustrated in Fig. 2; Fig. 4 is a crosssectional view taken on the line IV-IV of Fig. 3 and illustrates the arrangement of the strip aligning and edge-working means; Fig. 5 is a crossan ,angle to each other.

in this position not only facilitates their subsesectional view taken on the line V-V of Fig. 3 and illustrates the means for bending the strip to arcuate cross-sectional contour and for moving the strips through the welding means; Fig.6 is a cross-sectional view taken on the line VI--VI of Fig. 3 and illustrates the welding means; Fig. '7 is a cross-sectional view taken on the line VII-VII of Fig. 3 and illustrates the means for guiding and moving the strips through the welding means during the welding operation; Fig. 8 is a cross-sectional view taken on the line VIIIVIII of Fig. 3 and illustrates the means for flattening the composite sheet; Fig. 9 is a cross-sectional view taken on line IX-IX of Fig. 3 and illustrates the means for removing the bead formed during welding; and Fig. 10 is a crosssectional view taken transversely of the composite sheet after welding but before rolling and this view diagrammatically illustrates in exaggerated form the varying thickness of the strips comprising the sheet.

Referring particularly to Fig. l, which illustrates one form of apparatus which may be used to achieve the object of the invention, the numeral l indicates a'pair of furnaces adapted to.

receive and reheat slabs from which the strip is formed. Associated with the furnaces are charging and discharging means 2 which function to move the slabs after reheating onto a conveyor 4 having a tandem mill 8 incorporated therewith. The mill 6 rough-forms strip S from the slabs and is of the backed-up working roll type, that is, with two working rolls and two or more backing or pressure rolls which serve to support the working rolls during the rolling operation so that the rough strip S produced will be of the most uniform thickness possible. An important feature of the invention is that the various rolls and roll stands in mill 6 are relatively narrow so that for this reason also the strip formed is completely within commercial thickness tolerances. Moreover, the use of relatively narrow mills materially reduces installation and maintenance costs which mount rapidly as the widths of the mills are increased. From the mill 6 the strip passes to a coiler 8 where the strip is formed into coils l0. Associated with the coiler 8 is a conveyor I I which functions to carry the coils In to the welding unit, designated generally by the numeral l2.

The welding unit, as shown in Figs. 2 to 9,

comprises a suitable bed or frame l4 which at one end is provided with means 16 for supporting the 'coils of strip S. Passing from the coils ill the strips S are engaged by aligning and edgeworking means which in the embodiment of the invention shown comprise an upper roll l8 and a lower roll 20 which are driven by suitable and known means (not shown). As illustrated in Fig. 4 the rolls l8 and 20 are formed with cooperating surfaces which grip and hold the strips S so that their planes are at an angle to each other. Likewise the coil holders iii are preferably mounted at an angle to each other so that strips as pulled from the coils will have their planes at Holding the strips S quent bending into arcuate shape but likewise more readily permits their adjacent edges to be aligned and worked prior to the welding operation. Alignment and edge-working of .the strips is obtained by the provision of a trapezoidalshaped rib 22 formed at the center of the roll I8 which engages with and surfaces the edges of the strips. In order to hold the strips against the thrust of the rib 22 the roll 20 is formed with side flanges 24 having tapered surfaces parallel to the faces of the rib 22.

The edge-working rolls l8 and 20 likewise serve, together with the remaining mechanism hereafter described, to pull the strips S from the coils I I8 at a uniform speed so that the entire operation of the apparatus and the performance of the method is continuous.

After leaving the aligning and edge-working rolls the strips S pass to bending means so that after bending the strips conform in cross section substantially to an are or portion of a circle of relatively large diameter. As seen in Fig. 5 this bending operation is achieved in the particular form of the invention shown by the provision of rolls 28 and 30, driven in any desired manner, which have cooperating'convex and concave surfaces that grip the strips and bend them to arcuate form. The roll 30 is provided with side flanges having tapered surfaces 84 which engage with the outer edges of the strips S.

In order to insure the proper clearance between the adjacent strip edges to be welded the roll 28 is preferably provided with a guide rib 3 1, similar to but narrower than rib 22, which will maintain the edges in proper alignment as they are fed to the welding means. The bending of the strips to arcuate form gives them greater stability during the welding operation which is particularly desirable in relatively thin metal where a butt-weld is to be effected. The rolls 28 and 3!! in addition to bending the strips also serve to hold' them in proper position for welding as well as functioning to aid in moving the strips through the welding means.

Electric resistance welding means are employed for welding the strips together and these comprise a pair of circular electrodes 40 which as shown in Fig. 6 make electric and. mechanical contact with the edges of the strips to be welded. Cooperating with the electrodes 40 and serving to hold the strips S tightly against the electrodes and likewise functioning to push the edges of the strips to be welded tightly together, is an articulated bottom roll 42 having' side flanges formed with beveled faces 44 contacting in hard engagement with the outer edges of the strips S. The side flanges also prevent lateral slippage of the strips due to electrode pressure so that during welding a true upset weld is preferably produced to form a bead 46. The invention contemplates employing additional rolls 41 for assisting electrodes 40 and rolls 42 in holding the strips during welding. Any or all of the rolls may be driven but all are preferably driven by known means (not shown).

The arcuate cross-sectional shape of the strips facilitates the handling of the strips during welding in the same manner as atube, and the manner of effecting the weld and the resulting weld is quite similar likewise. To my knowledge this has never been done before and it constitutes a distinct advance in the art of welding strip. Al-

though described in conjunction with electric 56 after which the composite sheet passes to the means for removing the flash or bead 46 formed by welding and while this means may comprise a cutting tool or flash remover of any known standard design, I preferably employ adjustable grinding wheels 58 and 59 which engage with the bead at the top and bottom of the composite strip to grind it down flush with the surfaces of the sheet. The composite sheet is then coiled, as indicated at 60, on suitable mechanism 62 carried on the frame H.

Associated with the end of the welding unit is a conveyor 64 adapted to transmit the coil 68 to a finishing mill shown generally at 66. This mill 66 is preferably of the reversing type and has backed working rolls of the cluster or 4-high type so that roll deflection under pressure is reduced to a minimum. Coilers 68 are provided on both sides of the mill 66 in conjunction with known forms of conveyors. The composite sheet of considerable width is cold rolled on the wide finishing mill 66 to the desired size, surface and physical characteristics.

It should be understood that the welding unit in particular and the entire apparatus in general can be adapted to handle strip of different widths. This is preferably provided for by making the rolls throughout the entire apparatus readily changeable with rolls of other sizes. However, the invention contemplates also making the side flanges 24, 34, 44, etc. adjustable axially of the rolls to achieve the same end.

Considering Fig. 10, the strips S are illustrated after being butt-welded together at their edges to form a composite sheet. The curvature and the reduced gauge at the edges of the strip as well as the relative width and thickness have been exaggerated considerably in thedrawings in order to illustrate the general form of the strips as welded. The dotted line 10 illustrates, in somewhat exaggerated form, the contour of the sheet if made as a single full width piece from slab form. The relation of the full line and the dotted line contours is not exaggerated however and serves to strikingly illustrate the advantages of my invention and the superior article produced. When the composite sheet shown in Fig. 10 is subjected to cold rolling after welding, the thickness of the sheet is reduced to eliminate the uneven gauge adjacent the weld seam. A very uniform sheet having even thick ness transversely thereof is accordingly provided. It is believed that my improved process of manufacturing sheetmetal of uniform thickness will be evident from the foregoing descript on of the apparatus. Suffice it to say that strip of relatively narrow width is first formed to rough size on the narrow hot-rolling mill 6. Several of the strips are then coiled, mounted on the welding unit I2 and concurrently passed continuously to aligning and edge-working rolls I8 and 20 and from there to bending rolls 28 and 38 which form the strips arcuate in cross section. The strips continuously pass from the bending rolls to the welding rolls 4!! and 42 Where the strips are butt-welded together longitudinally by the electrical resistance method. This composite sheet is flattened by rolls 54 and 56 and the flash or head is ground off by grinding rolls 58 and 59. The sheet is then rolled into a coil 60 from which it is passed to the mill -66, which cold works the sheet to the desired dimensions and removes any channels or thin portions in the sheet adjacent the weld.

Sheet metal broadly, and more particularly sheet or strip metal of relatively thin gauge and great width formed according to my invention is free of wavy portions or buckles and at the same time is of very uniform thickness transversely. The apparatus for producing the improved sheet metal is relatively simple and is continuous and efficient in operation. The method of manufacture is an advance over the known processes of making sheet metal and results in an improved product.

While in accordance with the patent statutes one particular embodiment of my invention has been illustrated and described in detail it should be understood that the scope of the invention is not limited therebynor thereto but is defined in the appended claims.

I claim:

1. That method of manufacturing strip of very uniform thickness which comprises hot rolling metal on relatively narrow rolls to form relatively narrow rough strip which is within commercial thickness tolerances, continuously passing two pieces of the rough strip with their planes at an angle to each other, continuously aligning and working the adjacent edges of the strips, continuously bending the strips after edge working so that the strips in cross section form portions of a circle of relatively large diameter, continuously bringing the worked edges of the bent strip together in welding relation, continuously welding the engaging edges of the strip by the electric resistance method'to form a relatively wide composite strip, continuously flattening the composite strip, removing the bead formed by welding, and cold rolling the composite strip on relatively wide rolls to form it to the desired dimensions.

2. That method of manufacturing metal strip of very uniform thickness which comprises hot rolling metal to form rough strip, passing two pieces of the rough strip with their planes at an angle to each other, working the adjacent edges of the strips, bending the strips after edge working ,so that the strips in cross section form portions of a circle of relatively large diameter, bringing the worked edges of the bent strip together in welding relation, welding the engaging edges of the strip by the electric resistance method, flattening the composite strip, removing the bead formed by welding, and cold rolling the composite strip to form it to the desired dimensions.

3. That method of manufacturing sheet metal of very uniform thickness which comprises hot rolling metal to form roughstrip, bending the strips so that the strips in crosssection form portions of a circle of relatively large diameter, bringing the edges of the bent strip together in welding relation, welding the engaging edges of the strip by the electric resistance method, removing the bead formed by welding, flattening the composite strip, and cold rolling the composite strip to form itto the desired dimensions.

4. That method of manufacturing sheet metal of very uniform thickness which comprises hot rolling metal to form rough strip, bending the strips so that the strips in cross section form portions of a circle of relatively large diameter, bringing the edges of the bent strip together in Welding relation, welding the engaging edges of the strip, removing the bead formed by welding, and cold rolling the composite strip to form it to the desired dimensions.

5. That method of manufacturing sheet metal of very uniform thickness which comprises rolling metal to form rough strip, bending the strips so that the strips in cross section form portions of a circle of relatively large diameter, bringing the edges of the bent strip together in welding relation, welding the engaging edges of the strip, and rolling the composite strip to form it to the desired dimensions.

6. That method of manufacturing strip of very uniform thickness which comprises rolling metal to form rough strip, continuously passing two pieces of the rough strip with their planes at an angle to each other, continuously working the adjacent edges of the strips, continuously bending the strips after edge-working so that the strips in cross section form portions of a circle of relatively large diameter, continuously bringing the worked edges of the bent strip together in welding relation, and continuously welding the engaging edges of the strip.

'7. That method of manufacturing strip of very uniform thickness which comprises hot rolling metal to form rough strip, continuously passing two pieces of the rough strip with their planes at an'angle to each other, continuously aligning the adjacent edges of the strips, continuously bringing the aligned edges of the strip together in welding relation, continuously welding the engaging edges of the strip by the electric resistance method, continuously removing the bead formed by welding, and cold rolling the composite strip to form it to the desired dimensions.

8. The method of making wide strip metal of very even thickness across its width, comprising hot rolling relatively narrow strips of metal to rough form, butt-welding a plurality of the strips side to side to form a relatively wide composite strip, and then cold rolling the composite strip to the desired size.

9. The method of making wide sheet metal of very even thickness across its width, comprising hot rolling strips of metal to rough form, bending the strip so that in cross section it forms substantially an arc of a relatively large circle,, butt-welding a plurality of the strips edge to edge 11. Apparatus for making sheet metal comprising means for supporting a plurality of coils of strip, means for continuously pulling the strip from the supporting means with the planes of the strip at an angle to each other, means for continuously working adjacent edges of the strip, means for continuously bending the strip longitudinally so that it takes an arcuate shape, means for continuously butt-welding the edges of the bent strip, means for continuously flattening the composite sheet thus formed, means for continuously removing the bead at the weld, and means for continuously coiling the composite sheet.

12. Apparatus for making sheet metal comprising means for supporting a plurality of pieces of strip, with the planes of the strip at an angle to each other, means for aligning adjacent edges of the strip, means for bending the strip longitudinally so that it takes an arcuate shape, means for butt-welding the edges of the bent strip, and means for removing the bead at the weld.

13. That method of manufacturing wide sheet metal of uniform thickness which comprises hot rolling relatively narrow strips of metal to rough size, coiling the strips, mounting a plurality of the coils and continuously pulling the strips from the coils in substantially parallel paths, continuously cold working the adjacent edges of the strips, continuously butt-welding the strips together to form a composite strip, continuously coiling the composite strip, and cold rolling the composite strip to finished size.

14. That method of manufacturing wide sheet metal of uniform thickness which comprises hot rolling relatively narrow strips of metal to rough size, coiling the strips, mounting a plurality of the coils and continuously pulling the strips from the 'coils in substantially parallel paths, continuously butt-welding the strips together to form a composite strip, continuously coiling the composite strip, and cold rolling the composite strip to finished size.

15. Apparatus for making wide strip metal of thin but uniform gauge which comprises means for mounting a plurality of coils of relatively narrow strip metal, means for pulling the strips in substantially parallel paths from the mounted coils, means for cold working adjacent edges of the strips, means for continuously butt-welding the adjacent edges of the strips to form a wide composite strip, and means'i'or coiling the composite strip.

KIR'ILAND c. GARDNER. 

